We propose to utilize isolated fat cells of the rat to study in detail the mechanism by which insulin stimulates glucose transport. This will involve studies of the effect of energy inhibitors and cyclic AMP on rates of glucose transport measured in whole cells and isolated membrane vesicles. The major aim is to develop a system in which insulin action can be studied on a subcellular level using isolated membranes from fat cells and soluble extracts from fat cells, liver or muscle. Attempts to demonstrate an action of insulin on isolated membranes will be based on our recent demonstration that this is an energy-requiring process. We also plan to look at factors that can reverse the stimulation of glucose transport observed in membranes prepared from insulin-stimulated whole cells. In addition, we will pursue studies on changes in cell surface glycoproteins observed in diabetic animals. This will involve measurements of the binding of (125I) labeled lectins to isolated membranes prepared from control and diabetic animals. In addition, we will look at changes in other animal models of obesity and diabetes. We will study changes in glycoprotein biosynthesis and degradation in vivo in diabetic animals and in vitro with cell suspensions.